Aquatic pools, fishponds or fishing farms usually requires aeration devices to maintain the concentration of dissolved oxygen (DO), which is absolutely necessary and important to the breathing of aquatics, underwater organisms and microorganisms, the stabilization of water quality, and the ecological balance of aquatic pools. The microorganisms have to absorb dissolved oxygen from the water to decompose the redundant organic material and to perform nitrification, which transforms ammonia of higher toxicity into nitrous or nitric acid (NO2−, NO3−) of lower toxicities. A paddlewheel, a typical conventional aeration device, splashes the water into the air by its vane wheels driven by a motor, and it increases the contact time and surface area between the water droplets and air, so as to achieve the purposes of aeration and increasing the dissolved oxygen.
An aerobic treatment pool in a waste water treatment factory of the general environmental protection and the chemical industries also use microorganisms to decompose the organic materials in the water. In these applications, a blowing machine, an air pipe and air diffusers are typically used to transport air to the bottom of the pool, at which the air is transformed as a plurality of small air bubbles and released at the bottom of a pool. The mixing of small air bubbles and water increases the concentration of dissolved oxygen of the pool water, and, therefore, promotes the decomposition rate of the organic materials by microorganisms.
The efficiency of feeding oxygen increases with the increase of contacting surface area and the staying time of the bubbles in the water. Therefore, smaller bubbles are preferred. However, smaller gas outlets are much more likely to be adhered to and blocked by the microorganisms and suspended substances in the water. As a result, the air diffuser needs to be changed from time to time. The blowing machine and air diffuser are more suitable to be applied in an aerobic treatment pool associated with smaller water volumes and higher concentrations of BOD/COD. Aquatic pools are usually of much larger area and lower BOD/COD (between 10 ppm and 40 ppm), and their depths are between one and two meters. Therefore, the combination of blowing machine and air diffuser is not suitable to aquatic pools since the staying time of air bubbles is too short to an economical efficiency, and too many diffusers are required for large pools.
As a result, there is a need to provide a cost-effective method, which can greatly increase the concentration of dissolved oxygen close to the bottom of the pool.